diff --git a/sklearn/base.py b/sklearn/base.py
index 71e12985d..29c1e8161 100644
--- a/sklearn/base.py
+++ b/sklearn/base.py
@@ -363,7 +363,7 @@ class RegressorMixin:
 
         from .metrics import r2_score
         return r2_score(y, self.predict(X), sample_weight=sample_weight,
-                        multioutput='variance_weighted')
+                        multioutput='uniform_average')
 
 
 class ClusterMixin:
